Co-reporter:Chun-Guang Dai, Ji-Long Wang, Ying-Long Fu, Hong-Ping Zhou, and Qin-Hua Song
Analytical Chemistry October 3, 2017 Volume 89(Issue 19) pp:10511-10511
Publication Date(Web):September 11, 2017
DOI:10.1021/acs.analchem.7b02680
Nitric oxide (NO) is an important signaling molecule involved in many physiological and pathological processes. To understand these NO-mediated processes, it is a key to develop rapid and specific detection methods for NO. In the past 2 decades, numerous excellent fluorescent probes for NO have been designed; however, it still remains limitations such as slow response, low selectivity, and short excitation wavelength (<600 nm). In this Article, a two-photon fluorescent probe, NO-QA5, has been developed with 3-dimethylaminophenyl linking at the 6-position of 5-aminoquinoline as both the active site and prefluorophore for detection of NO. The nonfluorescent NO-QA5 can fast react with NO via a diazonium intermediate to generate two azoic regioisomers, one of which exhibits intramolecular charge transfer (ICT) emission, and two-photon absorption behavior (δΦ = 57 GM), giving a turn-on fluorescence rapid response. The sensing reaction is pH-insensitive in the range of 6–11 and highly selective and well sensitive (LOD = 15 nM), possible undergoing the same intermediate diazonium with the reaction under diazotization condition (NaNO2/HCl). Also, as a nitrite fluorescent probe NO-QA5 exhibits highly sensitive (LOD = 7 nM). Therefore, NO-QA5 can serve as a dual functional fluorescent probe for NO and NO2–. Furthermore, NO-QA5 as a specific imaging agent has been demonstrated by achieving both exogenous and endogenous detections of NO in living cells under both one- and two-photon excitation and high resolution in tissue slices under two-photon excitation.
Co-reporter:Hong-Cheng Xia, Xiang-Hong Xu, and Qin-Hua Song
Analytical Chemistry April 4, 2017 Volume 89(Issue 7) pp:4192-4192
Publication Date(Web):March 2, 2017
DOI:10.1021/acs.analchem.7b00203
As a highly toxic and widely used chemical, phosgene has become a serious threat to humankind and public security because of its potential use by terrorists and unexpected release during industrial accidents. For this reason, it is an urgent need to develop facile, fast, and selective detection methods of phosgene. In this Article, we have constructed a highly selective fluorescent sensor o-Pab for phosgene with a BODIPY unit as a fluorophore and o-phenylenediamine as a reactive site. The sensor o-Pab exhibits rapid response (∼15 s) in both colorimetric and turn-on fluorescence modes, high selectivity for phosgene over nerve agent mimics and various acyl chlorides and a low detection limit (2.7 nM) in solutions. In contrast to most undistinguishable sensors reported, o-Pab can react with phosgene but not with its substitutes, triphosgene and biphosgene. The excellent discrimination of o-Pab has been demonstrated to be due to the difference in highly reactive and bifunctional phosgene relative to its substitutes. Furthermore, a facile testing paper has been fabricated with poly(ethylene oxide) immobilizing o-Pab on a filter paper for real-time selective monitoring of phosgene in gaseous phase.
Co-reporter:Shao-Lin Wang;Lin Zhong
Chemical Communications 2017 vol. 53(Issue 9) pp:1530-1533
Publication Date(Web):2017/01/26
DOI:10.1039/C6CC09361B
A ratiometric fluorescent chemosensor, Phos-1, was constructed with 4,5-diaminonaphthalimide as a fluorophore for selective and visual detection of phosgene. The sensing mechanism was demonstrated to be the phosgene molecule acylating both amine groups of Phos-1. A test paper with Phos-1 was fabricated for facile, selective and visual detection of phosgene gas.
Co-reporter:Hong-Cheng Xia, Xiang-Hong Xu, and Qin-Hua Song
ACS Sensors - New in 2016 2017 Volume 2(Issue 1) pp:
Publication Date(Web):December 15, 2016
DOI:10.1021/acssensors.6b00723
The detection of highly toxic chemicals in a convenient, fast, and reliable manner is essential for coping with serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this paper, a highly selective fluorescent probe has been constructed through o-phenylenediamine covalently linking to coumarin (o-Pac), which can respond to phosgene in turn-on fluorescence mode. The response time is less than 0.5 min and the detection limit is as low as 3 nM in solutions. More importantly, the sensor exhibits good selectivity to phosgene over triphosgene and various acyl chlorides. Furthermore, a portable test paper has been fabricated with polystyrene membrane containing o-Pac for real-time selective monitoring of phosgene in gas phase.Keywords: chemical warfare agents; coumarin; fluorescent chemosensors; phosgene; triphosgene;
Co-reporter:Yuan-Chao Cai;Chen Li
Journal of Materials Chemistry C 2017 vol. 5(Issue 29) pp:7337-7343
Publication Date(Web):2017/07/27
DOI:10.1039/C7TC02617J
Nerve agents are highly toxic organophosphorus compounds, and their possible uses in terrorist attacks pose an immediate threat to public safety. Consequently, there is an urgent need to develop reliable and facile methods to detect these lethal chemicals. In this paper, three 6-substituted aminoquinolin oximes with different N-substituents have been constructed as donor–acceptor (D–A) chemosensors for a nerve-agent simulant, diethyl chlorophosphate (DCP). These D–A molecules exhibit a regular change in intramolecular charge transfer (ICT) character with the donating ability of the 6-amine. The hydroxyl of the oxime, as the active site, can be rapidly phosphorylated by DCP via nucleophilic substitution to the product HCl, which enables protonation at the nitrogen of the quinoline. The resulting product exhibits a longer wavelength of ICT emission relative to the corresponding sensor. Consequently, the three sensors respond to DCP in a ratiometric fluorescence mode. Among the three sensors, NA-p3 displays the most remarkable fluorescence change and the lowest limit of detection (21 nM) with DCP in solution. Furthermore, a facile test strip with NA-p3 has been fabricated that can achieve visual detection of DCP vapor and discriminate between DCP vapor and acidic gas in air.
Co-reporter:Mao Mao, Xiaolin Zhang, Bin Zhu, Jianbo Wang, Guohua Wu, Yan Yin, Qinhua Song
Dyes and Pigments 2016 Volume 124() pp:72-81
Publication Date(Web):January 2016
DOI:10.1016/j.dyepig.2015.09.002
•Four novel dyes with quinoline and quinazoline units as the π-bridges were designed.•4,4′-Dibutoxy diphenylamine unit as the donor leads to a better efficiency of DSSCs.•The highest cell efficiency was 2.51% for a quinoline-bridged dye.A new series of organic D–π–A dyes bearing either quinazoline or quinoline as the conjugated bridges in the chromophore with a diphenylamine moiety as the electron donor and a cyanoacetic acid unit as the electron acceptor, have been designed and synthesized for photoconversion in dye sensitized solar cells (DSSCs). The absorption spectra, density functional theory calculations, electrochemical and photovoltaic properties of these dyes are systematically investigated. Among the four dyes the sensitized solar cell based upon the quinoline dye bearing butoxy groups gave a short circuit photocurrent density of 7.04 mA cm−2, an open circuit voltage of 0.52 V, and a fill factor of 0.69, corresponding to an overall conversion efficiency of 2.51% using I−/−I3I3− redox couple-based liquid electrolyte without 4-tert-butylpyridine additives under standard global AM 1.5 irradiation (100 mW cm−2). The photovoltaic performance of the dye with 4,4′-dibutoxy diphenylamine as the donor and quinoline unit as the π-bridge was higher than that of the other photosensitizers, which is mainly attributed to the higher molar extinction coefficient and broader absorption band. The experimental results demonstrate that rational molecular engineering is crucial for constructing highly efficient charge transfer sensitizers.
Co-reporter:Chun-Guang Dai, Xiu-Ling Liu, Xiao-Jiao Du, Yan Zhang, and Qin-Hua Song
ACS Sensors 2016 Volume 1(Issue 7) pp:888
Publication Date(Web):June 1, 2016
DOI:10.1021/acssensors.6b00291
Development of multi-input fluorescent probes would facilitate the monitoring of multiple biomolecular events leading to a common disease pathology. Here, we reported a two-input fluorescent probe (QME-N3) based on quinoline scaffold with two distinct reactive sites, the α,β-unsaturated carbonyl at 2-site and 6-azido group, which were specific acceptors of RSH and H2S respectively. The turn-on fluorescent probe could react with the two molecules via the Michael addition at the double bond for RSH and the reduction of the azide by H2S without mutual interference, to generate the intensively fluorescent product, which could act as a two-input AND logic gate. Furthermore, QME-N3 has very low cytotoxicity and excellent stability, and the resulting sensing product has a high two-photon absorption cross section. Consequently, detection of intracellular thiols and H2S can be achieved by cell fluorescence imaging under both one- and two-photon excitations.Keywords: chemical inputs; fluorescent probes; H2S; molecular logic gate; recognition; thiols; two-photon imaging
Co-reporter:Mao Mao
The Chemical Record 2016 Volume 16( Issue 2) pp:719-733
Publication Date(Web):
DOI:10.1002/tcr.201500251
Co-reporter:Chun-Guang Dai, Xiao-Jiao Du, and Qin-Hua Song
The Journal of Organic Chemistry 2015 Volume 80(Issue 24) pp:12088-12099
Publication Date(Web):November 6, 2015
DOI:10.1021/acs.joc.5b02041
A Michael addition is usually taken as a base-catalyzed reaction. Most fluorescent probes have been designed to detect thiols in slightly alkaline solutions (pH 7–9). The sensing reactions of almost all Michael-type fluorescent probes for thiols are faster in a high pH solution than in a low pH solution. In this work, we synthesized a series of 7-substituted 2-(quinolin-2-ylmethylene)malonic acids (QMAs, substituents: NEt2, OH, H, Cl, or NO2) and their ethyl esters (QMEs) as Michael-type fluorescent probes for thiols. The sensing reactions of QMAs and QMEs occur in distinct pH ranges, pH < 7 for QMAs and pH > 7 for QMEs. On the basis of experimental and theoretic studies, we have clarified the distinct pH effects on the sensing reactivity between QMAs and QMEs and demonstrated that two QMAs (NEt2, OH) are highly sensitive and selective fluorescent probes for thiols in acidic solutions (pH < 7) and promising dyes that can label lysosomes in live cells.
Co-reporter:Xiu-Ling Liu, Xiao-Jiao Du, Chun-Guang Dai, and Qin-Hua Song
The Journal of Organic Chemistry 2014 Volume 79(Issue 20) pp:9481-9489
Publication Date(Web):September 25, 2014
DOI:10.1021/jo5014838
Hydrogen sulfide (H2S) is an important signaling molecule with diverse biological roles. Various fluorescent probes for H2S with biological application have been developed. However, two-photon ratiometric imaging of mitochondrial H2S is scarce. In this paper, we report two ratiometric two-photon probes, AcHS-1 and AcHS-2, which employ 4-amino-1,8-naphthalimide as the fluorophore and 4-azidobenzyl carbamate as the H2S response site. These probes exhibit high selectivity toward H2S over biothiols and other reactive species, low detection limits of 50–85 nM, low cytotoxicity, and high stability under physiological conditions. Furthermore, through cell imaging with one-photon and two-photon microscopy, MCF-7 cells incubated with two probes show a marked change in emission color from blue to green in response to H2S. Cell images costraining with a mitochondrial dye reveal that AcHS-2 is a mitochondria-specific two-photon probe for H2S. These results show that AcHS-2 may find useful applications in biological research such as tracking mitochondrial H2S in living biological specimens.
Co-reporter:Qing-Qing Wu;Zu-Feng Xiao;Xiao-Jiao Du; Qin-Hua Song
Chemistry – An Asian Journal 2013 Volume 8( Issue 11) pp:2564-2568
Publication Date(Web):
DOI:10.1002/asia.201300491
Co-reporter:Xiu-Ling Liu;Dr. Jian-Bo Wang;Yao Tong ;Dr. Qin-Hua Song
Chemistry - A European Journal 2013 Volume 19( Issue 39) pp:13216-13223
Publication Date(Web):
DOI:10.1002/chem.201300958
Abstract
The photochemical reaction of a pyrimidine and a ketone occurs either as a Paternò–Büchi (PB) reaction or as energy transfer (ET) from the triplet ketone to the pyrimidine. It is rare for the two types of reactions to occur concurrently, and their competitive mechanism remains unknown. In this work, two classes of products, regioisomeric oxetane(s) (2, 3) from a PB reaction and three isomeric dimers of 5-fluoro-1,3-dimethyl uracil (FDMU) (4–6) from a photosensitized dimerization of FDMU, are obtained through the UV irradiation of FDMU with various benzophenones (BPs). The ratio of the two products (oxetanes to dimers) reveals that the two competitive reactions depend strongly on the triplet energy levels (ET) of the BPs. The BPs with higher ET values lead to higher proportions of dimers, whereas those with lower ET values give higher proportions of oxetane(s), with the generation of just two regioisomeric oxetanes for the BP with the lowest ET of the eight BPs investigated. The ratio of the two oxetanes (2:3) decreases with the BP ET value. The competitive mechanism for the two types of photochemical reactions is demonstrated through quenching experiments and investigation of temperature effects. Kinetic analysis shows that the rate constants of the two [2+2] photocycloadditions are comparable. Furthermore, in combination with the results of previous studies, we have gained insight into the dependence of the photochemical type and the regioselectivity in the PB reaction on the triplet energy gaps (ΔE) between the pyrimidines and ketones. For ketones with higher ET values than the pyrimidines, the photochemical reaction is a photosensitized dimerization of the pyrimidine. In the opposite case, a PB reaction occurs, and the lower the ET of the ketones, the lower the ratio of oxetanes (2:3). When the ET of values of the ketones are close to those of the pyrimidines, the two reactions occur concurrently, and the higher the ET of the ketones, the higher the proportion of the dimers. The ratio of oxetanes (2:3) decreases with the ET value of the BPs.
Co-reporter:Ming-Guang Ren, Mao Mao and Qin-Hua Song
Chemical Communications 2012 vol. 48(Issue 24) pp:2970-2972
Publication Date(Web):17 Jan 2012
DOI:10.1039/C2CC17663G
Excited-state conversions were observed from a series of twisted pyrene-substituted tridurylboranes, corresponding to a locally excited (LE) state, a more planar charge transfer (CT) state with a higher fluorescence quantum efficiency, and a more twisted CT state.
Co-reporter:Jian-Bo Wang, Qing-Qing Wu, Yuan-Zeng Min, Yang-Zhong Liu and Qin-Hua Song
Chemical Communications 2012 vol. 48(Issue 5) pp:744-746
Publication Date(Web):28 Nov 2011
DOI:10.1039/C1CC16128H
A novel fluorescent probe for gold ions (Au3+/Au+) is reported through blocking photoinduced electron transfer, in which a boron dipyrromethene (Bodipy) derivative reveals high selectivity and sensitivity in a gold-catalyzed intramolecular hydroamination, and is successfully applied to fluorescence imaging of Au3+ in living cells.
Co-reporter:Mao Mao, Qin-Hua Song
Dyes and Pigments 2012 Volume 92(Issue 3) pp:975-981
Publication Date(Web):March 2012
DOI:10.1016/j.dyepig.2011.08.020
Three porphyrin-cored dendrimers with non-conjugated coumarins as dendrons have been synthesized and characterized. The photophysical properties of the title compounds were investigated by means of UV/Vis absorption and fluorescence spectroscopy in dilute CH2Cl2 solutions and in thin neat films. The intramolecular energy transfer from the coumarin units to the porphyrin core clearly reveals two factors influencing energy-transfer efficiency. Firstly, a better spectral overlap between the absorption spectrum of porphyrin core and the emission spectrum of the coumarin moiety results in high energy-transfer efficiency. Secondly, a long alkyl side-chain improves solubility of dendrimers, but also prevents the coumarins from self-quenching. Hence, the dendrimer with N-octyl groups possesses a higher efficiency than that with N-ethyl groups. The dendrimers emit red light with higher fluorescence quantum yields over the free porphyrin.Highlights► Three non-conjugated dendrimers with a centered porphyrin were synthesized. ► Efficient energy transfer in dendrimers was observed, ΦFRET ∼99%. ► Two factors influencing energy-transfer efficiency were demonstrated.
Co-reporter:Mao Mao, Jian-Bo Wang, Zu-Feng Xiao, Song-Yuan Dai, Qin-Hua Song
Dyes and Pigments 2012 Volume 94(Issue 2) pp:224-232
Publication Date(Web):August 2012
DOI:10.1016/j.dyepig.2012.01.011
A series of new metal-free organic dyes with either a boron dipyrromethene (BODIPY)-phenylene or -thiophene as a π-conjugated bridge have been synthesized for application in dye-sensitized solar cells. The photophysical and electrochemical properties of these dyes were investigated and their performance as sensitizers in dye-sensitized solar cells has been measured. The structure–property relationship shows that the introduction of a methoxy group as the donor and a BODIPY-thiophene unit as the π-conjugated bridge are favorable to improve the efficiency of DSSCs. A combination of a methoxy modified donor and BODIPY-thiophene bridge possesses a stronger electron-donating ability and longer wavelength absorption band, and as a sensitizer reveals the best properties of DSSCs, whose conversion efficiency was 2.26%.Highlights► A series of new 2,6-modified BODIPY dyes were synthesized for DSSCs. ► The highest overall efficiency, 2.26%, was achieved among these BODIPY dyes. ► Several factors influencing the efficiency of DSSCs were demonstrated.
Co-reporter:Xue-You Duan, Bao-Chang Zhai and Qin-Hua Song
Photochemical & Photobiological Sciences 2012 vol. 11(Issue 3) pp:593-598
Publication Date(Web):14 Feb 2012
DOI:10.1039/C2PP05309H
Two new o-hydroxycinnamates have been prepared for photoremovable protecting groups, and their photochemistry has been investigated. The photolysis of two caged compounds can efficiently release the corresponding alcohol in aqueous solutions, and the uncaging reaction proceeds with large one-photon excitation cross sections (1919 and 1535 M−1 cm−1). The uncaging process has been observed by NMR spectroscopy. The caged compounds exhibit good aqueous solubility and excellent resistance to hydrolysis in a buffer solution.
Co-reporter:Dr. Mao Mao;Dr. Ming-Guang Ren ; Dr. Qin-Hua Song
Chemistry - A European Journal 2012 Volume 18( Issue 48) pp:15512-15522
Publication Date(Web):
DOI:10.1002/chem.201201719
Abstract
We synthesized a series of donor-substituted tridurylboranes containing different types and number of chromophores including 1-pyrene (PB1–3), 3-carbazole (CBC1–3), or substituted p-carbazol-N-phenyl (CBN3a–c) as various donor–acceptor (D–A) molecules. The photophysical and electrochemical properties of these twisted D–A molecules were investigated by means of UV/Vis absorption and fluorescence spectroscopy as well as cyclic voltammetry (CV). Solvent polarity, viscosity, and temperature effects on the fluorescence emission reveal the existence of three types of excited states, and their equilibria and interconversions between three excited states. In increasing order of the charge-separated extent and the conformational change, three excited states are the locally excited (LE) state, the more planar intramolecular charge-transfer (ICT) state, and the more twisted ICT (TICT) state as compared to the ground state. The TICT state undergoes a conformational change with a higher energy barrier over the ICT state. The solvent polarity effect on the state conversion is opposite to the viscosity effect, and temperature effects derive from its resulting changes of polarity and viscosity. For example, the increase of the polarity of the solvent results in excited-state conversions from the LE state to the ICT state, and/or from the ICT to the TICT state, and an increased viscosity leads to the opposite conversions. On the basis of electrochemical and spectral data, thermodynamics of a possible ICT process were estimated, and correlated with the excited-state character. Finally, three excited states have been characterized by the conformation, the photophysical properties, and the thermodynamics of the ICT processes.
Co-reporter:Dr. Wenjian Tang;Hongmei Zhou;Jing Wang;Chunxiao Pan;Dr. Jingbo Shi; Qinhua Song
ChemPhysChem 2012 Volume 13( Issue 18) pp:4180-4185
Publication Date(Web):
DOI:10.1002/cphc.201200652
Abstract
In chromophore-containing cyclobutane pyrimidine dimer (CPD) model systems, solvent effects on the splitting efficiency may depend on the length of the linker, the molecular conformation, and the oxidation potential of the donor. To further explore the relationship between chromophore structure and splitting efficiency, we prepared a series of substituted indole–T<>T model compounds 2 a–2 g and measured their splitting quantum yields in various solvents. Two reverse solvent effects were observed: an increase in splitting efficiency in solvents of lower polarity for models 2 a–2 d with an electron-donating group (EDG), and vice versa for models 2 e–2 g with an electron-withdrawing group (EWG). According to the Hammett equation, the negative value of the slope of the Hammett plot indicates that the indole moiety during the T<>T-splitting reaction loses negative charge, and the larger negative value implies that the repair reaction is more sensitive to substituent effects in low-polarity solvents. The EDGs of the models 2 a–2 d can delocalize the charge-separated state, and low-polarity solvents make it more stable, which leads to higher splitting efficiency in low-polarity solvents. Conversely, the EWGs of models 2 e–2 g favor destabilization of the charge-separated state, and high-polarity solvents decrease the destabilization and hence lead to more efficient splitting in high-polarity solvents.
Co-reporter:Jian-Bo Wang;Xia-Qin Fang;Dr. Xu Pan; Song-Yuan Dai; Qin-Hua Song
Chemistry – An Asian Journal 2012 Volume 7( Issue 4) pp:696-700
Publication Date(Web):
DOI:10.1002/asia.201100779
Co-reporter:Xiu-Ling Liu;Xue-You Duan;Xiao-Jiao Du;Dr. Qin-Hua Song
Chemistry – An Asian Journal 2012 Volume 7( Issue 11) pp:2696-2702
Publication Date(Web):
DOI:10.1002/asia.201200594
Abstract
A new type of fluorescent probes for thiophenols, 6HQM-DNP and 7HQM-DNP, containing 6- or 7-hydroxy quinonlinium as fluorophore and 2,4-dinitrophenoxy (DNP) as nucleophilic recognition unit were constructed. As ethers, these non-fluorescent probe molecules can release the corresponding fluorescent quinolinium (6HQM and 7HQM) through aromatic nucleophilic substitution (SNAr) by thiolate anions from thiophenols. The sensing reaction is highly sensitive (detection limit of 8 nM for 7HQM-DNP) and highly selective to thiophenols over aliphatic thiols and other nucleophiles under neutral conditions (pH 7.3). The probes respond rapidly to thiophenols, with second-order rate constants k=45 M−1 s−1 for 7HQM-DNP and 24 M−1 s−1 for 6HQM-DNP. Furthermore, the selective detection of thiophenols in living cells by 7HQM-DNP was demonstrated by confocal fluorescence imaging. In addition, these quinolinium salts show excellent chemical and thermal stability. In conclusion, this type of probes may find use in the detection of thiophenols in environmental samples and biosystems.
Co-reporter:Ming-Guang Ren, Hui-Jun Guo, Fei Qi and Qin-Hua Song
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 20) pp:6913-6916
Publication Date(Web):01 Jul 2011
DOI:10.1039/C1OB05857F
A series of pyrene-centered starburst oligocarbazoles (1–3) have been synthesized and well characterized. Based on photophysical, thermal and electrochemical studies in solutions and as thin films, all starburst molecules reveal a sky blue emission with a high efficiency (ΦF = 0.99 − 0.81) and excellent thermal and electrochemical stabilities. As OLED materials, these superior properties are helpful to enhance device stability and lifetime.
Co-reporter:Mao Mao, Qing-Qing Wu, Ming-Guang Ren and Qin-Hua Song
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 9) pp:3165-3169
Publication Date(Web):14 Feb 2011
DOI:10.1039/C1OB05072A
In contrast to the reversible photochemistry of the 2,2′-substituted bixanthenylidenes (1a–f), the photocyclization of 2,2′-diacyl bixanthenylidenes (1g–j) reveals an irreversible process where the initial cyclic intermediate C(E) can undergo a rapid [1,11] hydrogen shift to form stable isomer C′(E) in a degassed solution, which cannot revert to the starting compound, so giving a highly efficient and regiospecific photocyclization.
Co-reporter:Hong-Wei Chen, Qin-Hua Song, Bing Liao, and Qing-Xiang Guo
Energy & Fuels 2011 Volume 25(Issue 10) pp:4655
Publication Date(Web):September 3, 2011
DOI:10.1021/ef201016a
Effective separation methods must be developed before bio-oils become a source of chemical products or liquid fuels by further upgrading. Phase separation is one effective pathway to realize an initial isolation of bio-oils. When aqueous salt solutions are added, phase separation of the pyrolysis bio-oil can occur to form two different phases: the upper layer with high contents of water, acetic acid, and water-soluble compounds and the bottom layers with low water content and high lignin pyrolysis compounds [Song, Q.-H.; Nie, J.-Q.; Ren, M.-G.; Guo, Q.-X.Effective phase separation of biomass pyrolysis oils by adding aqueous salt solutions. Energy Fuels 2009, 23 (6), 3307−3312]. In this paper, the salt-induced phase separation of bio-oils with 20 kinds of salt solutions was investigated. On the basis of the dependence of the mass ratio of the bio-oil bottom layer to the whole bio-oil sample upon the salt solution concentrations, it has been demonstrated that the phase separation derives from a normal ionic strength effect as well as chemical properties for some metal ions. Solvent fractionations of the two-phase bio-oils were performed, and fractions were characterized by elemental and gas chromatography/mass spectrometry (GC/MS) analyses. Among the four bottom-layer bio-oil fractions, fraction A contains insoluble macromolecular substances, such as cellulose, and fractions, B, C, and D are mainly phenolic compounds. Furthermore, O-methylation of the mixtures of fractions B, C, and D with dimethyl carbonate (DMC) has been performed in ionic liquid [Bmin]Cl, and the reaction is highly effective and recyclable for the ionic liquid. The modified mixture of the fractions reveals a large elevation in the heating value.
Co-reporter:Ming-Guang Ren, Mao Mao, Xue-You Duan, Qin-Hua Song
Journal of Photochemistry and Photobiology A: Chemistry 2011 Volume 217(Issue 1) pp:164-168
Publication Date(Web):1 January 2011
DOI:10.1016/j.jphotochem.2010.10.004
A new synthesis method of hydrogen peroxide was investigated by the photoreduction of 2-ethylanthraquinone (AQ) in water-insoluble organic solvents. Through optimizing the photoreduction condition including solvent, atmosphere and irradiated time, the photolysis system of 1,3,5-trimethylbenzene/trioctyl phosphate (3:1) solvent mixture under oxygen atmosphere was found to give a high yield of hydrogen peroxide. Furthermore, the formation mechanism of hydrogen peroxide was proposed, i.e. photoreduction and subsequent oxidation of AQ. The photoreduction of 2-ethylanthraquinone undergoes the hydrogen abstraction from solvent to form the anthrahydroquinone, which is subsequently oxidized by oxygen to give hydrogen peroxide.
Co-reporter:Qing-Qing Wu ; Xue-You Duan
The Journal of Physical Chemistry C 2011 Volume 115(Issue 48) pp:23970-23977
Publication Date(Web):October 21, 2011
DOI:10.1021/jp207812a
The development of molecular arithmetic systems is very crucial for the realization of a molecule-scale calculator (a Moleculator). In this work, two compounds with pH-sensitive functional groups, 2-quinolin-2-ylmethylene-malonic acids (QMA-1 and QMA-2), have been prepared for molecular algebraic operations. These compounds can exist in several ionization forms (cationic, neutral, and anionic), each of which has distinct spectral properties, and can be applied in the construction of acid/base-boosted molecular Boolean arithmetic functions including half-subtractor, half-adder, full-subtractor, and full-adder. A half adder x + y and a bidirectional half-subtractor, x – y and y – x, have been obtained on the basis of the absorption of QMA-1, whose absorption values at certain wavelengths are applied as signal outputs, using a base as chemical input. A molecular full-adder x + y + Cin and a molecular full-subtractor x – y – Bin have also been achieved through utilizing a combined fluorescence from a single solution containing both QMA-1 and QMA-2 as output signals and acid/base as chemical inputs. These systems are resettable after each separate arithmetic operation.
Co-reporter:Jun-Qi Nie, Hong-Wei Chen, Qin-Hua Song, Bing Liao, and Qing-Xiang Guo
Energy & Fuels 2010 Volume 24(Issue 10) pp:5722-5726
Publication Date(Web):September 15, 2010
DOI:10.1021/ef1008659
O-Methylation of phenols has been studied as an important organic reaction, and its products, aryl methyl ethers, are valuable intermediates in fine chemicals. The phenolic component is one of the factors leading to the thermal instability of biomass pyrolysis oils. O-Methylation of phenols is helpful to improve the stability of bio-oil. Using dimethyl carbonate (DMC) as a methylation reagent, model O-methylations of three phenols (phenol, guaiacol, and eugenol) have been investigated in an ionic liquid, 1-butyl-3-methylimidazolium chloride ([bmim]Cl), in the presence of water and carboxylic acid, separately. In [bmim]Cl at 130 °C, both hydrolysis of DMC and esterification of acetic acid with DMC would occur and compete with the O-methylation of phenol and decrease the yield of the methylation. However, the esterification of carboxylic acids is helpful for bio-oil upgrading. Under the same reaction conditions, the methylation was performed for a phenolic bio-oil, which is the ether extractive from the bottom layer of phase separation of a biomass pyrolysis oil by adding a salt solution. Gas chromatography/mass spectrometry (GC/MS) analysis showed that phenolic compounds in the bio-oil were converted completely to the corresponding aryl methyl ethers and carboxylic acids were esterified to the corresponding methyl esters. The phenolic bio-oil after the modification has greatly enhanced the heating value, more than 30%. The methylation of the phenolic bio-oil with DMC in [bmim]Cl may be a potential method for upgrading of bio-oil.
Co-reporter:Qing-Qing Wu and Qin-Hua Song
The Journal of Physical Chemistry B 2010 Volume 114(Issue 30) pp:9827-9832
Publication Date(Web):July 8, 2010
DOI:10.1021/jp1035579
Although many similarities exist between the two classes of enzymes, cyclobutane photolyases and (6−4) photolyases have certain important differences. The most significant difference is in their repair quantum yields, cyclobutane photolyases with a uniformly high efficiency (0.7−0.98) and very low repair efficiency for (6−4) photolyases (0.05−0.1). To understand the significant difference, we prepared two classes of model compounds, covalently N-linked dimer- (1) or oxetane-carbazole (2) compounds with a dimethylene or trimethylene group as a linker. Under light irradiation, the dimer or oxetane unit of model compounds can be sensitized to split by the excited carbazole via an intramolecular electron transfer. The splitting reaction of dimer or oxetane unit in model compounds is strongly solvent dependent. In nonpolar solvents, such as cyclohexane or THF, no fluorescence quenching of the carbazole moiety of model compounds relative to a free carbazole, N-methylcarbazole, was observed and thus no splitting occurred. In polar solvents, two classes of model compounds reveal two reverse solvent effects on the splitting quantum yield. One is an inverse relation between the quantum yield and the polarity of the solvent for dimer-model systems, and another is a normal relation for oxetane-model systems. This phenomenon was also observed with another two classes of model compounds, covalently linked dimer- or oxetane-indole. Based on Marcus theory and thermodynamic data, it has been rationalized that the two reverse solvent effects derive from back electron transfer in the splitting process lying in the different Marcus regions. Back electron transfer lies in the Marcus inverted region for dimer-model systems and the normal region for oxetane-model systems. From repair solvent behavior of the two classes of model compounds, we gained some insights into the major difference in the repair efficiency for the two classes of photolyases.
Co-reporter:Qin-Hua Song, Jun-Qi Nie, Ming-Guang Ren and Qing-Xiang Guo
Energy & Fuels 2009 Volume 23(Issue 6) pp:3307
Publication Date(Web):April 29, 2009
DOI:10.1021/ef900143u
Effective separation methods must be developed to generate fractions of similar polarity and to concentrate the undistillable compounds before bio-oils are to be a source of chemicals production. Phase separation is one effective pathway to realize initial separation of bio-oil. By adding a little salt (3 wt % of bio-oil) or aqueous salt solution (10 wt % of bio-oil) including LiCl, CaCl2, FeCl3, (NH4)SO4, K2CO3, and Fe(NO3)3, the pyrolysis bio-oil of rice husk would quickly form two phases (40−80 wt % of the upper phase, 20−60 wt % of the bottom phase). On the basis of elemental analysis, 13C NMR integrations and GC/MS analysis, it has been demonstrated that some major components in the bio-oil are concentrated in upper/bottom phases respectively. The upper layers exhibit high contents of water, acetic acid, and water-soluble compounds; low density, viscosity, and calorific values; and high distillable substances (up to 65%). The bottom layer consists of low water content, high lignin-pyrolysis compounds, and low distillable substances (<10%), with high viscosity and calorific values. The physiochemical properties of two phases from the phase separation depend on the nature and dosage of salt added.
Co-reporter:Wen-Jian Tang, Qing-Xiang Guo and Qin-Hua Song
The Journal of Physical Chemistry B 2009 Volume 113(Issue 20) pp:7205-7210
Publication Date(Web):April 30, 2009
DOI:10.1021/jp805965e
In model studies involving the mechanisms of DNA photolyases, two reverse solvent effects on the quantum yield of photosensitized splitting of a cyclobutane pyrimidine dimer (CPD) by a covalently linked chromophore have been reported. One is an increase in the splitting efficiency in lower polarity solvents for model compounds with a short linker between the dimer and the chromophore. Another is more efficient splitting in higher polarity solvents for model compounds with a flexible and long linker. To unravel mechanisms of two opposite solvent effects, five covalently linked indole−dimer compounds with different-length linkers were prepared. Two solvent effects as described above were observed through measuring quantum yields of dimer splitting of these model compounds in four solvents. According to Marcus theory, back electron transfer in the splitting reaction was analyzed quantitatively in light of relative data of a model compound in four solvents. It was demonstrated that the dependence of the quantum yield on solvent polarity for the flexible long-linker system would derive from the change in the distance between a dimer unit (acceptor) and an indole moiety (electron donor) in different solvents. With increasing solvent polarity, a U-shaped conformation of the model compound would become a preferred conformation because of the hydrophobic interaction between indole and dimer moiety, and their distances would become closer. On the basis of Marcus theory, calculated results reveal that the rate of back electron transfer would be slowed down with increasing solvent polarity and the distance reduced, giving a more efficient splitting. Meanwhile, some new insights into mechanisms of DNA photoreactivation mediated by photolyases were gained.
Co-reporter:Ming-Guang Ren, Nai-Min Bi, Mao Mao, Qin-Hua Song
Journal of Photochemistry and Photobiology A: Chemistry 2009 Volume 204(Issue 1) pp:13-18
Publication Date(Web):30 April 2009
DOI:10.1016/j.jphotochem.2009.02.006
Using anthraquinone 2-yl ethyl (Aqe) as a photolabile protecting group for carboxylic acids, five caged compounds, Aqe esters of p-methoxybenzoic acid (1a), o-methylbenzoic acid (1b), benzoic acid (1c), p-nitrobenzoic acid (1d) and N-acetyl-l-tryptophan (1e), have been prepared, and their photochemistry was investigated. Upon 350 nm light irradiation, three caged compounds 1a–c in methanol solutions can efficiently release the corresponding carboxylic acids, their quantum yields ranging from 0.12 to 0.08. The intramolecular triplet–triplet energy transfer and the intramolecular electron transfer between triplet anthraquinone and the caged acids may occur, leading to a low efficiency of caged compounds 1d and 1e, respectively. Furthermore, based on quenching experiments, HPLC and spectral analysis, the mechanism of the uncaging reaction was suggested.
Co-reporter:Feng-Feng Kong, Bao-Chang Zhai and Qin-Hua Song
Photochemical & Photobiological Sciences 2008 vol. 7(Issue 11) pp:1332-1336
Publication Date(Web):18 Aug 2008
DOI:10.1039/B810640A
The [2 + 2] photochemical cycloadditions (the Paternò–Büchi reaction) of 5- or/and 6-methyl substituted uracil derivatives with 4,4′-disubstituted benzophenones generate two series of regioisomeric oxetanes, 3 and 4. The regioselectivity (3/4) and the photochemical efficiency are strongly dependent on methyl substituent(s) at the C5–C6 double bond of the uracils. The more the methyl groups at the C5–C6 double bond, the higher the efficiency. The regioselectivity (3/4) ranges from ca. 20:80 for 1,3,6-trimethyluracil (1C) to ca. 80:20 for 1,3,6-trimethylthymine (1D). The substituent effects would derive from the hyperconjugation of the methyl group(s) at C5 or/and C6 of the uracils, which influences the stability of intermediary triplet 1,4-biradicals and the nucleophilicity of C5 and C6 sites of the double bond. Computational studies reveal that potential energies of triplet 1,4-biradicals forming oxetanes 3, BR5, are 1–4 kcal mol−1 higher than those of 1,4-biradicals forming oxetanes 4, BR6, and electron densities at C5 are 0.1–0.3 unit higher than those at C6, of the double bond of the uracils, i.e. BR5 are less stable than BR6, and BR5 form more easily than BR6. Temperature effects on the regioselectivity of the Paternò–Büchi reaction of 1D with three benzophenones (2a–c) reveal that efficiencies of oxetanes 3 are higher at a lower reaction temperature, and efficiencies of 4 are higher at a higher temperature. Therefore, triplet biradicals BR5 and BR6 would be regarded as intermediates of kinetic control and thermodynamic control, respectively.
Co-reporter:Xi-Bo Li
Heteroatom Chemistry 2007 Volume 18(Issue 3) pp:203-207
Publication Date(Web):9 APR 2007
DOI:10.1002/hc.20236
The reaction mechanism and solvent-dependant regioselectivity of 1,3-dipolar cycloaddition reactions between azide and acetylene derivatives have been studied using computational methods. The two possible reaction transition states were located. Geometry and NBO analysis found that the reactions take place along a synchronous and concerted mechanism for TS1 and an asynchronous and less concerted mechanism for TS2. SCRF analysis found that TS2 is more sensitive to the polarity of solvent. In less polar solvent such as CCl4, the difference of activation barriers of the two transition states is small. However, when the reactions were conducted in water, the activation barriers for TS2 increase which leads to the observed regioselectivity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:203–207, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20236
Co-reporter:Qin-Hua Song Dr.;Wen-Jian Tang Dr.;Xue-Bao Ji;Hong-Bo Wang Dr.;Qing-Xiang Guo
Chemistry - A European Journal 2007 Volume 13(Issue 27) pp:
Publication Date(Web):14 JUN 2007
DOI:10.1002/chem.200700251
cis–syn Cyclobutane pyrimidine dimers, major UV-induced DNA lesions, are efficiently repaired by DNA photolyases. The key step of the repair reaction is a light-driven electron transfer from the FADH− cofactor to the dimer; the resulting radical anion splits spontaneously. Whether the splitting reaction requires considerable activation energy is still under dispute. Recent reports show that the splitting reaction of a dimer radical anion has a significant activation barrier (0.45 eV), and so photolyases have to provide considerable energy. However, these results contradict observations that cis–syn dimer radical anions split into monomers at −196 °C, and that the full process of DNA photoreactivation was fast (1.5–2 ns). To investigate the activation energies of dimer radical anions, three model compounds 1–3 were prepared. These include a covalently linked cyclobutane thymine dimer and a tryptophan residue (1) or a flavin unit (3), and the covalently linked uracil dimer and tryptophan (2). Their properties of photosensitised splitting of the dimer units by tryptophan or flavin unit were investigated over a large temperature range, −196 to 70 °C. The activation energies were obtained from the temperature dependency of splitting reactions for 1 and 2, 1.9 kJ mol−1 and 0.9 kJ mol−1 for the thymine and uracil dimer radical anions, respectively. These values are much lower than that obtained for E. coli photolyase (0.45 eV), and are surmountable at −196 °C. The activation energies provide support for previous observations that repair efficiencies for uracil dimers are higher than thymine dimers, both in enzymatic and model systems. The mechanisms of highly efficient enzymatic DNA repair are discussed.
Co-reporter:Bao-Chang Zhai, Shi-Wei Luo, Feng-Feng Kong, Qin-Hua Song
Journal of Photochemistry and Photobiology A: Chemistry 2007 Volume 187(2–3) pp:406-409
Publication Date(Web):15 April 2007
DOI:10.1016/j.jphotochem.2006.10.028
Notable solvent effects on the regioselectivity and the photochemical efficiency were observed in the Paternò–Büchi (PB) reaction of 1,3-dimethylthymine (DMT) with 4-methoxybenzophenone (MBP). As a comparison, photochemical reactions of 4,4′-difluorobenzophenone (DFBP) and benzophenone (BP) with DMT were performed under the same condition. With increasing the proportion of water in the solution, besides the PB reaction, an electron-transfer reaction was observed in the DFBP–DMT system. The PB reaction of BP–DMT system revealed similar effects on the regioselectivity and the efficiency with that of MBP–DMT system, but the latter is more remarkable. The notable solvent effects may be responsible for a strongly solvent-dependent properties of the excited triplet MBP.
Co-reporter:Jing-yu Yu, Wen-Jian Tang, Hong-Bo Wang, Qin-Hua Song
Journal of Photochemistry and Photobiology A: Chemistry 2007 Volume 185(Issue 1) pp:101-105
Publication Date(Web):1 January 2007
DOI:10.1016/j.jphotochem.2006.05.010
A new photolabile protecting group for aldehydes and ketones, 2-(1,2-dihydroxyethyl) anthraquinone (Aqe-diol) and four caged compounds have been prepared and their photochemistry investigated. Upon 350 nm light irradiation, the caged compounds 2a-d in CH3CN–H2O solution can efficiently release the carbonyl compounds (conversion rate 60–90%), and their uncaging quantum efficiencies were measured, ranging from 0.03 to 0.09. On the basis of HPLC analysis and quenching experiments, a mechanism of the uncaging reaction was suggested.
Co-reporter:Qin-Hua Song, Kuo Chu Hwang
Journal of Photochemistry and Photobiology A: Chemistry 2007 Volume 185(Issue 1) pp:51-56
Publication Date(Web):1 January 2007
DOI:10.1016/j.jphotochem.2006.05.009
Using the fast optical technique of laser flash photolysis by a kinetic absorption detector, the photophysical and photochemical processes of folic acid have been observed. By comparison of transient absorptions from photolysis between folic acid and its components, pteroic acid, pterin and 6-carboxypterin, it has been demonstrated that electron-transfer reactions from 4-aminobenzoyl group to the triplet pterin moiety occur through intra- and inter-molecular processes of folic acid. The intermolecular electron-transfer reaction is suggested to be mediated by two tautomers of triplet states of folic acid, lactim and lactam, in different rate constants, 1.4 × 109 and 1.6 × 108 M−1 s−1, respectively.
Co-reporter:Wen-Jian Tang, Qin-Hua Song, Hong-Bo Wang, Jing-yu Yu and Qing-Xiang Guo
Organic & Biomolecular Chemistry 2006 vol. 4(Issue 13) pp:2575-2580
Publication Date(Web):2006/05/26
DOI:10.1039/B604529D
Two modified β-cyclodextrins (β-CDs) with a thymine dimer and a thymine oxetane adduct respectively, TD-CD and Ox-CD, have been prepared, and utilized to bind an electron-rich chromophore, indole or N,N-dimethylaniline (DMA), to form a supramolecular complex. We have examined the photosensitized splitting of the dimer/oxetane unit in TD-CD/Ox-CD by indole or DMA via an electron-transfer pathway, and observed high splitting efficiencies of the dimer/oxetane unit. On the basis of measurements of fluorescence spectra and splitting quantum yields, it is suggested that the splitting reaction occurs in a supramolecular complex by an inclusion interaction between the modified β-CDs and DMA or indole. The back electron transfer, which leads low splitting efficiencies for the covalently-linked chromophore–dimer/oxetane compounds, is suppressed in the non-covalently-bound complex, and the mechanism has been discussed.
Co-reporter:Qin-Hua Song, Hong-Bo Wang, Wen-Jian Tang, Qing-Xiang Guo and Shu-Qin Yu
Organic & Biomolecular Chemistry 2006 vol. 4(Issue 2) pp:291-298
Publication Date(Web):07 Dec 2005
DOI:10.1039/B514921E
Three covalently linked tryptophan–thymine oxetane compounds used as a model of the (6–4) photolyase–substrate complex have been prepared. Under 290 nm light, efficient splitting of the thymine oxetane with aromatic carbonyl compounds gives the thymine monomer and the corresponding carbonyl compounds by the covalently linked tryptophan via an intramolecular electron transfer, and exhibits a strong solvent dependence: the quantum yield (Φ) is ca. 0.1 in dioxane, and near 0.3 in water. Electron transfer from the excited tryptophan residue to the oxetane unit is the origin of fluorescence quenching of the tryptophan residue, and is more efficient in strong polar solvents. The splitting efficiency of the oxetane radical anion within the tryptophan˙+–oxetane˙− species is also solvent-dependent, ranging from ca. 0.2 in dioxane to near 0.35 in water. Thus, the back electron transfer reaction in the charge-separated species would be suppressed in water, but is still a main factor causing low splitting efficiencies in the tryptophan–oxetane systems. In contrast to the tryptophan–oxetane system, fast nonradiation processes are the main causes of low efficiency in the flavin–oxetane system. Hence, nonradiative processes of the excited FADH−, rather than electron transfer to oxetane, may be an important factor for the low repair efficiency of (6–4) photolyase.
Co-reporter:Qin-Hua Song;Bao-Chang Zhai;Xiao-Ming Hei;Qiang-Xiang Guo
European Journal of Organic Chemistry 2006 Volume 2006(Issue 7) pp:
Publication Date(Web):31 JAN 2006
DOI:10.1002/ejoc.200500862
The photochemical [2+2] cycloadditions (the Paternò–Büchi reaction) of 1,3-dimethylthymine (DMT) or 1,3-dimethyluracil (DMU) with benzophenone and its six 4,4′-disubstituted derivatives (BPs) generate two series of regioisomeric oxetanes, the head-to-head (hh) oxetanes 2 or 4 and the head-to-tail (ht) oxetanes 3 or 5. The PB reactions reveal notable substituent effects on their regioselectivity, photochemical efficiency as well as their stability and the mode of ring-opening. The regioselectivity and the photochemical efficiency correlate clearly with the electronic properties of the substituents of the BPs, that is, the BPs with electron-withdrawing groups (EWGs) give more efficient PB reactions with a lower proportion of the hh oxetane and less efficient PB reactions with a higher proportion of the hh oxetane for BPs with electron-donating groups (EDGs). The oxetanes from DMT, 2 and 3, are more stable than the corresponding oxetanes from DMU, 4 and 5. The oxetanes from the BPs with EWGs are more stable than the corresponding oxetanes formed from the BPs with EDGs. The ring-opening modes of the oxetanes are also dependent on the DMT/DMU and BPs in the presence of acid.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Co-reporter:Hong-Bo Zhuang;Wen-Jian Tang;Jing-Yu Yu
Chinese Journal of Chemistry 2006 Volume 24(Issue 10) pp:
Publication Date(Web):2 OCT 2006
DOI:10.1002/cjoc.200690276
Synthesis and photochemistry of acridin-9-ylmethoxycarbonyl (Amoc) as a new photochemically removable protecting group for alcohols were described. Three carbonates of alcohols 1–3 were synthesized through condensation of 9-hydroxymethylacridine and chloroformates of alcohols, including benzyl alcohol, phenethyl alcohol and one galactose derivative. The photolysis of protected alcohols can efficiently release the corresponding alcohol in the efficiencies (Qu1ε) of 100–200 (quantum yield Qu1=0.011–0.023, and molar absorptivity ε=9.1×103–9.8×103 mol−1·L·cm−1) under 360 nm light.
Co-reporter:Qin-Hua Song, Hong-Bo Wang, Xi-Bo Li, Xiao-Ming Hei, Qing-Xiang Guo, Shu-Qin Yu
Journal of Photochemistry and Photobiology A: Chemistry 2006 Volume 183(1–2) pp:198-204
Publication Date(Web):30 September 2006
DOI:10.1016/j.jphotochem.2006.03.018
The photochemical [2 + 2] cycloadditions (the so-called Paternò-Büchi (PB) reaction) of 1,3-dimethyluracil (DMU) and 1,3-dimethylthymine (DMT) with benzophenone (1d) and its derivatives (BPs) with 4,4′-disubstituted groups including CH3O (1a), CH3 (1b), t-Bu (1c), F (1e), Cl (1f) and CN (1g) generate two series of regioisomeric oxetanes, A and B, and reveal notable substituent effects on the regioselectivity (A:B) and the photochemical efficiency, that is a higher ratio of A:B and lower efficiency for the BPs with electron-donating groups (EDGs), and a contrary effect for the BPs with electron-withdrawing groups (EWGs), such as A:B ≥ 95:5 for 1a to 32:68 for 1g in DMU photochemical system. The PB reactions of DMU with three BPs (1d, 1e and 1g) were performed at various temperatures, and temperature effects on the regioselectivity and the efficiency were observed. The ratio of photoproducts (A:B) in the DMU systems decreases with increasing the reaction temperature, such as DMU–1d system, ranging from 75:25 at −30 °C to 55:45 at 60 °C. On the basis of computational studies, the substituent effects were relationalized in terms of stability and charge distribution of intermediary triplet diradicals. The EWGs can stablize triplet diradicals especially the diradicals causing oxetanes B, and a destablization for EDGs. It was demonstrated that temperature effects originate from the conformational properties of intermediatary triplet diradicals.
Co-reporter:Yan Li-Qin;Song Qin-Hua;Hei Xiao-Ming;Guo Qing-Xiang;Lin Wei-Zhen
Chinese Journal of Chemistry 2003 Volume 21(Issue 1) pp:
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20030210106
The oxidative splitting process of cis-syn 1,3-dimethyluracil cyclobutane dimer (DMUD) in aqueous solution was investigated using pulse radiolysis technique. The results indicated that DMUD can be splitted into 1,3-dimethyluracil (DMU) by OH radicals (OH·) and Br2 radical anions (Br·2−), but not by azide radicals (N·3). The oxidative mechanisms that an H-abstracted from DMUD for OH· oxidative splitting and an electron transfer from DMUD to Br·2−, were suggested. Related kinetic parameters were determined.
Co-reporter:Mao Mao, Qing-Song Li, Xiao-Lin Zhang, Guo-Hua Wu, Chun-Guang Dai, Yong Ding, Song-Yuan Dai, Qin-Hua Song
Dyes and Pigments (June 2017) Volume 141() pp:
Publication Date(Web):June 2017
DOI:10.1016/j.dyepig.2017.02.017
•Molecular energy level tuning could be accomplished by alternating the donor moiety.•The best reported efficiency of 4.76% was achieved with the DSSCs based on TPA-B.•The TPA chromophore is favorable to improve the efficiency of Bodipy-based cell.A new series of donor-acceptor-π-linker-acceptor (D–A–π–A) featured organic dyes containing Bodipy derivative as the auxiliary acceptor, furan unit as the π conjugated spacer, and 2-cyanoacrylic acid as the anchor group were synthesized and applied in dye-sensitized solar cells (DSSCs). The incorporated electron-withdrawing unit of Bodipy enhances light harvesting by decreasing the molecular energy gap and red-shifting absorption spectra. For comparison, three different arylamine chromophores namely 3-methoxy-9H-carbazole (CBZ-B), triphenylamine (TPA-B) and phenoxazine (POZ-B) were separately appended onto the 6-position of Bodipy unit to study the effect of the electron donating groups on device performance. The UV–vis absorption spectra, electrochemical properties, density functional theory calculation, photovoltaic properties and electrochemical impedance measurements of DSSCs with these three dyes were systematically investigated. The Bodipy dyes have broad absorption spectra covering the range of 250–700 nm with the highest molar extinction coefficient up to >55 000 M−1 cm−1. The molecular energy level tuning can be conveniently accomplished by alternating the donor moiety. The DSSCs based on TPA-B showed the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 70%, a short-circuit photocurrent density (Jsc) of 13.95 mA cm−2, an open-circuit photovoltage (Voc) of 557 mV, and a fill factor (ff) of 0.61, corresponding to an overall conversion efficiency of 4.76% under standard global AM 1.5G solar light conditions. Our research demonstrates that Bodipy based D–A–π–A molecular architecture is a highly promising class for the improvement of the performance of DSSCs in the future.
Co-reporter:Jian-Bo Wang, Qing-Qing Wu, Yuan-Zeng Min, Yang-Zhong Liu and Qin-Hua Song
Chemical Communications 2012 - vol. 48(Issue 5) pp:NaN746-746
Publication Date(Web):2011/11/28
DOI:10.1039/C1CC16128H
A novel fluorescent probe for gold ions (Au3+/Au+) is reported through blocking photoinduced electron transfer, in which a boron dipyrromethene (Bodipy) derivative reveals high selectivity and sensitivity in a gold-catalyzed intramolecular hydroamination, and is successfully applied to fluorescence imaging of Au3+ in living cells.
Co-reporter:Ming-Guang Ren, Mao Mao and Qin-Hua Song
Chemical Communications 2012 - vol. 48(Issue 24) pp:NaN2972-2972
Publication Date(Web):2012/01/17
DOI:10.1039/C2CC17663G
Excited-state conversions were observed from a series of twisted pyrene-substituted tridurylboranes, corresponding to a locally excited (LE) state, a more planar charge transfer (CT) state with a higher fluorescence quantum efficiency, and a more twisted CT state.
Co-reporter:Ming-Guang Ren, Hui-Jun Guo, Fei Qi and Qin-Hua Song
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 20) pp:NaN6916-6916
Publication Date(Web):2011/07/01
DOI:10.1039/C1OB05857F
A series of pyrene-centered starburst oligocarbazoles (1–3) have been synthesized and well characterized. Based on photophysical, thermal and electrochemical studies in solutions and as thin films, all starburst molecules reveal a sky blue emission with a high efficiency (ΦF = 0.99 − 0.81) and excellent thermal and electrochemical stabilities. As OLED materials, these superior properties are helpful to enhance device stability and lifetime.
Co-reporter:Shao-Lin Wang, Lin Zhong and Qin-Hua Song
Chemical Communications 2017 - vol. 53(Issue 9) pp:NaN1533-1533
Publication Date(Web):2017/01/04
DOI:10.1039/C6CC09361B
A ratiometric fluorescent chemosensor, Phos-1, was constructed with 4,5-diaminonaphthalimide as a fluorophore for selective and visual detection of phosgene. The sensing mechanism was demonstrated to be the phosgene molecule acylating both amine groups of Phos-1. A test paper with Phos-1 was fabricated for facile, selective and visual detection of phosgene gas.
Co-reporter:Yuan-Chao Cai, Chen Li and Qin-Hua Song
Journal of Materials Chemistry A 2017 - vol. 5(Issue 29) pp:NaN7343-7343
Publication Date(Web):2017/07/05
DOI:10.1039/C7TC02617J
Nerve agents are highly toxic organophosphorus compounds, and their possible uses in terrorist attacks pose an immediate threat to public safety. Consequently, there is an urgent need to develop reliable and facile methods to detect these lethal chemicals. In this paper, three 6-substituted aminoquinolin oximes with different N-substituents have been constructed as donor–acceptor (D–A) chemosensors for a nerve-agent simulant, diethyl chlorophosphate (DCP). These D–A molecules exhibit a regular change in intramolecular charge transfer (ICT) character with the donating ability of the 6-amine. The hydroxyl of the oxime, as the active site, can be rapidly phosphorylated by DCP via nucleophilic substitution to the product HCl, which enables protonation at the nitrogen of the quinoline. The resulting product exhibits a longer wavelength of ICT emission relative to the corresponding sensor. Consequently, the three sensors respond to DCP in a ratiometric fluorescence mode. Among the three sensors, NA-p3 displays the most remarkable fluorescence change and the lowest limit of detection (21 nM) with DCP in solution. Furthermore, a facile test strip with NA-p3 has been fabricated that can achieve visual detection of DCP vapor and discriminate between DCP vapor and acidic gas in air.
Co-reporter:Mao Mao, Qing-Qing Wu, Ming-Guang Ren and Qin-Hua Song
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 9) pp:NaN3169-3169
Publication Date(Web):2011/02/14
DOI:10.1039/C1OB05072A
In contrast to the reversible photochemistry of the 2,2′-substituted bixanthenylidenes (1a–f), the photocyclization of 2,2′-diacyl bixanthenylidenes (1g–j) reveals an irreversible process where the initial cyclic intermediate C(E) can undergo a rapid [1,11] hydrogen shift to form stable isomer C′(E) in a degassed solution, which cannot revert to the starting compound, so giving a highly efficient and regiospecific photocyclization.
Co-reporter:Chun-Guang Dai, Ji-Long Wang and Qin-Hua Song
Journal of Materials Chemistry A 2016 - vol. 4(Issue 41) pp:NaN6733-6733
Publication Date(Web):2016/09/27
DOI:10.1039/C6TB02081J
Selenocysteine (Sec), which is a biological selenol incorporated into selenoproteins specifically, plays vital roles in physiological processes and cancer treatment. However, there are limited fluorescent probes for selective detection of Sec and in only one case is a near-infrared (IR) fluorescent probe applied in biological imaging of Sec in living animals. In this work, we have synthesized a new fluorophore, boron-dibenzopyrromethene (B-Bodipy), with an absorption maximum at 650–660 nm, and constructed two deep red fluorescent probes, Sel-p1 and Sel-p2, which are two ethers composed of a 2,4-dinitrobenzenoxy and B-Bodipy moiety. Experiments in solution show that the two probes can react effectively with selenols to release the fluorophore via aromatic nucleophilic substitution (SNAr), with a low limit of detection (16 nM and 9 nM), high selectivity and excellent photostability. The potential application for the detection of Sec in cells has been demonstrated by cell imaging experiments of Sel-p2, including detection of exogenous Sec and selenite-induced Sec in living cells. Furthermore, Sel-p2 as a red fluorescent probe can achieve the detection of Sec in animals by mice imaging experiments.
